Magnetic mechanical amplifier

ABSTRACT

An apparatus for converting electrical pulses into amplified mechanical motion. Two magnetic core pieces retain a resilient spring so that an air gap exists between the cores. By energizing a magnetic coil on at least one of the core pieces, the core pieces are attracted together thereby forcing the deformable spring to arc outwardly and produce an amplified linear motion. The actuator is particularly useful for operating print hammers, wires or punches.

1 United States Patent 1 1 H 1 3,754,199 Lisinski Aug. 21, 1973 [54] MAGNETIC MECHANICAL AMPLIFIER 2,692,965 10/1954 Bachi 335/275 X 3,072,045 1/1963 Goin [75] 3,459,126 8/1969 Nyman 101/93 c Raton, Fla.

[73] Assignee: International Business Machines P im ry Ex miner-George Harris Corporation, Armonk, NY. Attorney-tanley M, MilEr, Earl C Hancock et a1. 2 22 F! d: Se 1. 29, 197 1 p 2 57 ABSTRACT [21] 293;, An apparatus for converting electrical pulses into amplified mechanical motion. Two magnetic core pieces [5 US- Cl 335/275, 335/276, WI /93 C retain a resilient spring so that an air gap exists between [51] Int. Cl. H01! 7/08 the cores. By energizing a magnetic coil on at least one [58] Field oi Search... 335/275, 276, 28]; 0f the core pieces, the core pieces are attracted to- 101/93 C gether thereby forcing the deformable spring to arc outwardly and produce an amplified linear motion. The [56] References Cited actuator is particularly useful for operating print ham- UNITED STATES PATENTS Wes Punches- 984,748 2/1911 Coleman 335/276 X 7 Claims, 5 Drawing Figures MAGNETIC MECHANICAL AMPLIFIER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to electromechanical switching or actuation devices employing magnetic elements and, in particular, to devices of this type which are used to control print hammers, wires, punches, latches, bails, etc.

2. Description of the Prior Art Print hammers, punches and other control devices have used electromagnetic actuation in many different ways. These devices employ magnetostrictive action to provide mechanical displacements that are used to control the print hammers or other control devices. Some of these devices have the electromagnet being energized to attract the control device or to attract an arm which strikes the control device. Other types of actuators use permanent magnets held down by an energized coil which is de-energized to allow the magnet to fly open for the mechanical actuation. An example of an electromechanical actuator using a hold coil and an actuating back coil is shown in U.S. Pat. No. 3,449,639, Actuator Drive Circuit, by Brown et al. which issued June 10, 1969. An improvement to an actuator similar to Brown et al. wherein the hold coil is replaced with a permanent magnet is shown in U.S. Pat. No. 3,659,238, Permanent Magnet Electromagnetic Actuator, by B. M. Griffing which issued Apr. 25, 1972. Both the aforementioned patents are assigned to the same assignee as this invention. This type of magnet is in general the more expensive.

Modern printing assemblies comprising a number of print elements in a print head require as small and compact a design as possible. The compactness of a print element is largely dependent on the size of the magnet coil needed to energize the magnets. Any design which reduces the size of the magnet coil will necessarily have to be operable with lower power requirements. However, a reduction in power to the magnets will also require the air gap in the magnetic flux path be relatively small so that lower power can draw the magnets together to bring about mechanical motion. The problem with decreasing the air gap size is that doing this to prior art devices would reduce'the mechanical movement at the required position; i.e., the print position. Thus, in order to reduce the air gap size and be able to take advantage of a smaller magnet coil, it is necessary that such a print element amplify the speed at which the gap is closed at the print position. The prior art mechanisms do not amplify the motion at the air gap and therefore need a sufficient size air gap, and therefore larger coil, to develop sufficient speed at the print position.

Therefore, the primary object of this invention is to transfer the closing of a small air gap between two magnets into a higher velocity and amplified motion at another position.

' A further object of this invention is to provide an improved actuating mechanism that can be operated with a low power magnet coil.

A still further object of this invention is to provide an improved actuating mechanism that is both compact and flat.

Another object of this invention is to provide an actuating device that only requires a relatively small air gap in the magnetic circuit but which is capable of realizing a relatively large mechanical movement at the printing or punching position.

One of the advantages of any device which can work with a short duration and low current actuation of the coil is a lack of a problem with heat dissipation. This invention operated on a current of 800 900 milliamps for 500 microseconds will not create enough heat to harm the device. Therefore, no heat dissipation apparatus needs to be included.

SUMMARY OF THE INVENTION The present invention is a simple magnet structure that furnishes great mechanical amplification of motion from a small magnetic air gap. Two magnetic core pieces are retained at one end by a flexible spring hinge and by a deformable bow spring at the other end. The two magnetic core pieces are held slightly apart from each other via the deformable bow spring. A low power magnetic coil on at least one of the core pieces is energized to attract the core pieces together thereby forcing the deformable spring to bow or arc outwardly and to produce amplified linear motion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a preferred embodiment of the present invention showing a single magnetic mechanical amplifier with the resilient spring in its quiescent state and its bowed state.

FIG. 2 is a schematic front view of the magnetic mechanical amplifier of this invention.

FIG. 3 shows the geometry used to obtain the magnetic air gap displacement ratios.

FIG. 4 shows both an alternate arrangement of the basic components of an actuator element and a multiple element configuration as they might be arranged in a printer assembly.

FIG. 5 shows a fiberglass unitary spring as another embodiment of the actuator element of this invention.

DETAILED DESCRIPTION A preferred embodiment of the present invention is shown in FIGS. 1 and 2. Two fiat magnetic cores 2 and 3 are held together at one end by a spring hinge 4 attached to the cores by suitable screws 6. Ifsome lateral movement of the cores were present, suitable means could be added to prevent it. A flexible spring 8 is anchored to the end of each magnet core in such a way that a slight air gap 10 is opened betweenthe two magnet cores. A magnet coil 12 of sufi'icient ampere-turns is placed on either or both legs of the magnet cores to energize the magnet in order to close the air gap. A print hammer 14 is attached to the center of the flexible spring to cause printing upon activation of the spring when the magnetic cores are brought together. It should be recognized to those skilled in the art that wires, punches, latches, bails, etc. could be substituted for the print hammers for use in many other applications without departing from the scope of this invention.

Another embodiment of the actuator with the same basic components placed in a multiple element configuration such as might be arranged in a printer assembly is shown in FIG. 4. This print head 18 contains eight actuator elements with a 0.1 inch horizontal spacing and a 0.0156 inch vertical spacing between them at the print positions. In this embodiment the print assembly 18 is moved along platen 20 generating characters in the form of a dot pattern created by the print wires 22. Thus, the character height in this embodiment would be approximately 8 dots high. Because the actuator elements are vertically displaced of each other, the printing is not done on the exact center line of the platen. This does not present a problem in practice, however, when the vertical spacing is so small as is the case herein. If the vertical spacing were greater, a more flat platen could be used. A matrix printer could be composed of one or more of these print assemblies. If more than one of these print assemblies were used, then each print assembly would only have to travel 8 positions across the platen. This would be faster than one print assembly but conversely would be more expensive. The high speed attained by this compact actuator element makes it very useful in a matrix printer of this type. The actuator element of FIG. 4 has two coils, 23 and 24, one on each magnet, with the magnets so constructed to make the assembly of the coil and the magnets easy. The main reason for using two coils instead of one is that two coils can be made thinner and yet supply the same amount of current as one bigger coil. Furthermore, the use of two coils results in a more even magnetic flux distribution. Flexible spring hinge 25 is attached to the magnets and curved away from the magnets so that the pivot point of the hinge is at axle 26. Axle 26 supports all the actuator elements. With a hinge such as this, the pivot point for the elements is displaced from the magnets and the air gap spacing between the magnets is more uniform over the length of the magnets. This embodiment further shows a snubber 28 on end bow spring 30 which prevents vibration when the bow spring returns from its actuated position when the gap is opened. This embodiment shows matrix print wires 22 instead of the print hammer of the first embodiment. Means for controlling the timing of pulses 3] to the printing coils is also shown in FIG. 4, one such means being a general purpose computer.

In FIG. 4, the wires 22 could be arranged vertically by rotating the print assembly 90 and removing the 0.0156 displacement. With the wires arranged in such a straight line vertical arrangement, the print assembly could be used as a serial matrix printer which would be compatible with existing serial matrix printers.

FIG. shows still another alternate embodiment of the actuator element of this invention. This embodiment has a unitary fiberglass spring and frame 32. In this embodiment the hinge needed to pivot the magnets and the bow spring are made from one piece of fiberglass.

In operation, an electrical pulse of short duration energizes the coil or coils which causes the magnetic cores to be attracted to one another. As shown in FIG. I, the flexible bow spring 8 will be forced outward as the magnetic cores come together thus bringing the ends of the spring closer together. The spring thus "pops out" or bows further, as shown by reference numeral 14, at a high velocity resulting in an amplification of movement at the print position over that across the air gap between the magnets.

FIG. 3 shows the geometry used to obtain the magnetic air gap displacement ratios, i.e., the ratio between the displacement of the bow spring to the air gap between the magnets. With point 0 as the pivot point for bow or displacement of the spring. The air gap between the magnet cores is the distance between the length of side BC and the hypotenuse BE; in practice, however. the spring bows slightly which requires that the chord of the arc be used for computation rather than the hypotenuse. However, this distance is insignificant.

As can be seen clearly in FIG. 2, the width of the mechanism is directly related to the necessary size of the magnet coil 12. The present invention has the advantage of having high speed in magnetic operation due to a small air gap. Furthermore, the present invention can operate with lower power requirements and yet have the necessary speed of movement at the print or punch position because of flexible spring action.

While the novel features and aspects of the present invention have been shown and described with reference to the preferred embodiment thereof, it will be understood by those skilled in the art that many changes in form and detail other than those mentioned herein may be made without departing from the spirit and scope of the invention.

I claim:

1. A device for converting electrical pulse energy into mechanical motion comprising a pair of magnetic devices arranged to define a magnetic flux path,

retaining means on one side of said magnetic devices which retains said magnetic devices so that said magnetic devices pivot at that end,

a flexible bow device retained by the'other side of said magnetic devices in such a manner that an air gap exists between said devices,

and

means for introducing a magnetic flux into at least one of said magnetic devices whereby said magnetic devices will be attracted towards one another so as to cause said bow device to flex in a mechanical amplified movement.

2. The device defined in claim 1 wherein said flexible bow device is flexed in an arc outwardly away from said magnetic devices.

3. The device defined in claim 1 wherein said flux introducing means is a coil.

4. The device defined'in claim 1 wherein said flux introducing means consists of one coil on each of said magnets.

5. The device defined in claim 1 further including vibration snubbing means attached to said flexible bow device to hit the magnetic devices as the bow device moves toward said magnetic devices to prevent said bow spring from advancing beyond a predetermined position to prevent vibration.

6. A device for converting electrical pulse energy into mechanical motion comprising a pair of magnetic devices arranged to define a magnetic flux path,

retaining means on one side of said magnetic devices which retains said magnetic devices so that said magnetic devices pivot at that end, a portion of said retaining means being space from said magnetic devices such that the pivot point is spaced from said magnetic devices,

a flexible bow device retained by the other side of said magnetic devices in such a manner that an air gap exists between said devices,

and

a flexible bow device retained by the other side of said magnetic devices in such a manner that an air gap exists between said devices,

a coil associated with at least one of said magnetic devices, and v means for controlling the timing of electrical pulses to said coils whereby said magnetic devices will be attracted towards one another so as to cause said bow device to flex in a mechanical amplified movement. 

1. A device for converting electrical pulse energy into mechanical motion comprising a pair of magnetic devices arranged to define a magnetic flux path, retaining means on one side of said magnetic devices which retains said magnetic devices so that said magnetic devices pivot at that end, a flexible bow device retained by the other side of said magnetic devices in such a manner that an air gap exists between said devices, and means for introducing a magnetic flux into at least one of said magnetic devices whereby said magnetic devices will be attracted towards one another so as to cause said bow device to flex in a mechanical amplified movement.
 2. The device defined in claim 1 wherein said flexible bow device is flexed in an arc outwardly away from said magnetic devices.
 3. The device defined in claim 1 wherein said flux introducing means is a coil.
 4. The device defined in claim 1 wherein said flux introducing means consists of one coil on each of said magnets.
 5. The device defined in claim 1 further including vibration snubbing means attached to said flexible bow device to hit the magnetic devices as the bow device moves toward said magnetic devices to prevent said bow spring from advancing beyond a predetermined position to prevent vibration.
 6. A device for converting electrical pulse energy into mechanical motion comprising a pair of magnetic devices arranged to define a magnetic flux path, retaining means on one side of said magnetic devices which retains said magnetic devices so that said magnetic devices pivot at that end, a portion of said retaining means being space from said magnetic devices such that the pivot point is spaced from said magnetic devices, a flexible bow device retained by the other side of said magnetic devices in such a manner that an air gap exists between said devices, and means for introducing a magnetic flux into at least one of said magnetic devices whereby said magnetic devices will be attracted towards one another so as to cause said bow device to flex in a mechanical amplified movement.
 7. A print assembly comprising in combination one or more print elements each further comprising a pair of magnetic devices arranged to define a magnetic flux path, retaining means on one side of said magnetic devices which allows said magnetic devices to pivot at that side, a flexible bow device retained by the other side of said magnetic devices in such a manner that an air gap exists between said devices, a coil associated with at least one of said magnetic devices, and means for controlling the timing of electrical pulses to said coils whereby said magnetic devices will be attracted towards one another so as to cause said bow device to flex in a mechanical amplified movement. 